Research study finds dogs have bigger brains than cats because they are more sociable

If you ever find yourself involved in one of those clichéd conversations about whether you’re a dog or cat person; you might want to cite this little snippet of information.

Back in 2010, researchers at Oxford University concluded that over millions of years dogs have developed bigger brains than cats. This, they claim, is because highly social species of mammals need more brainpower than solitary animals.

Headed by Dr Susanne Shultz and Professor Robin Dunbar, from Oxford University’s Institute of Cognitive and Evolutionary Anthropology (ICEA), the study attempted to chart the evolutionary history of the brain across different groups of mammals over a 60 million year time span.

The researchers discovered that there are huge variations in how the brains of different groups of mammals have evolved over that time.

The study also explored the notion that there is a link between the sociality of mammals and the size of their brains relative to body size.

The cooperation needed for group living can be challenging and over time dogs have evolved larger brains to cope with the demands of socialising.

The research team analysed available data on the brain size and body size of more than 500 species of living and fossilised mammals.

It found that the brains of monkeys grew the most over time, followed by horses, dolphins, camels and dogs. All of which are known to be highly social species of mammal.

The results support the idea that groups of mammals with relatively bigger brains tend to live in stable social groups.

On the other end of the scale, the brains of more solitary mammals, such as cats, deer and rhino, grew significantly slower during the same period.

The discovery of the wide variation of brain growth in mammals, and that not all mammal groups have evolved larger brains, suggests that social animals need to think more.

Lead author Dr Susanne Shultz, a Royal Society Dorothy Hodgkin Fellow at ICEA, said: “This study overturns the long-held belief that brain size has increased across all mammals. Instead, groups of highly social species have undergone much more rapid increases than more solitary species.”

“This suggests that the cooperation and coordination needed for group living can be challenging and over time some mammals have evolved larger brains to be able to cope with the demands of socialising.”

Co-author and Director of ICEA Professor Robin Dunbar said: “For the first time, it has been possible to provide a genuine evolutionary time depth to the study of brain evolution.”

“It is interesting to see that even animals that have contact with humans, like cats, have much smaller brains than dogs and horses because of their lack of sociality.”

So there it is in a nutshell. Professors at Oxford University have concluded that due to dogs being more sociable, they have much larger brains than cats. Make of that, exactly what you will.

S. Shultz, R. Dunbar. Encephalization is not a universal macroevolutionary phenomenon in mammals but is associated with sociality. Proceedings of the National Academy of Sciences, 2010; DOI: 10.1073/pnas.1005246107